1. Field of the Invention
The present invention relates to surveillance camera systems, and, more particularly, to a surveillance camera gimbal mechanism.
2. Description of the Related Art
A typical external camera adjustment mechanism may move the entire housing subassembly of a camera, and thus, the viewing direction of the camera is more easily discerned by the observer. Thus, a person under surveillance is able to take evasive action to avoid being viewed by the camera. A typical implementation of an external mechanism is a manually-adjusted mount that is fixed at the time of installation and then maintains the same camera position during operation. External adjustment mechanisms that operate under remote control can be used to allow continuous repositioning of the camera during operation, but still may be avoided by a person under surveillance. Typical pan-tilt adjustment mechanisms require a larger operating envelope because the tilt axis is offset from the center of the camera housing, and thus has a larger operating range of movement.
A hemispherical window may be used to contain the external adjustment mechanism. In this configuration, the adjustment mechanism is contained inside the housing such that the housing does not move relative to the surrounding objects under surveillance. A position of the camera is out of easy view of the person under surveillance, especially if an opaque, hemispherical, and covert liner is placed inside the hemispherical window to obscure most views of the camera and mask its silhouette within the hemispherical window.
In early designs, the camera was positioned inside the hemispherical window on a mechanism similar to that described above where the tilt axis offset necessitated that the hemisphere diameter was large to accommodate a full range of motion. Subsequent improvements in the mechanism using a yoke-type mechanism to position the tilt axis more toward the center of the camera allowed for a smaller operating envelope, which has resulted in much smaller and less obtrusive hemispherical window housings.
However, typical adjustment mechanisms force an installer to manipulate and tighten multiple fasteners for the tilt, pan, and diagonal adjustments. Furthermore, fasteners located on a rotational axis must be tightened very tight to be stable. Additionally, lock washers used with the on-axis fasteners may develop depressions in the mating parts that favor certain angular positions, thereby making it more difficult for the installer to set a new angular position. Finally, the diagonal adjustment range is limited by the structural topography of typical adjustment slots used for diagonal adjustment.
Furthermore, typical prior art cameras do not include a compliant element to allow lens displacement if an external impact deflects the hemispherical window, especially when the impact is applied to the apex of the hemisphere.
What is needed in the art is a surveillance camera gimbal mechanism which provides an improved adjustment mechanism.